Fuel injection systems for internal combustion engines with automatic variation of the advance of fuel injection



July 31, 1962 p. E. BESSIERE 3,

FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES WITH AUTOMATICVARIATION OF THE ADVANCE OF FUEL INJECTION Filed Dec. 5, 1960 FZ TZ 1113INVENTOR Farr: Ifinws gas/er:

ATTORNEYS 3,46,93 Patented July 31, 1352 3,946,963 1 lJnL IIJJEC'I'iGNSYSTEMS FOR INTERNAL M- BUSTHON ENGHNES WITH AUTOMATIC VARiA- TION 0FTim ADVANCE 0F FUEL INJECTION Pierre Etienne Bessiere, 55 Blvd.Commandant Charcot,

Neuiliy-sur-Seine, France Filed Dec. 5, 1960, Ser. No. 73,857 Claimspriority, application France Dec. 10, 1959 13 Claims. (Cl. 123-439) Thepresent invention relates to fuel injection systems for internalcombustion engines with automatic variation of the advance of fuelinjection.

There are known systems of this kind which include a threaded sleeveadapted to be moved axially and serving to connect the driving shaft, ora shaft driven by said driving shaft at a speed proportional to thespeed thereof,

to a rotating member which produces, through suitablev mechanical meanssuch as cams, connecting rods, links, eccentrics, etc., the axialreciprocating movement of the fuel injection pump piston, at least inone direction..

It is also known to produce the axial displacement of said sleeve bymeans of a hydraulic ram or jack acting against a return force under theeffect of a pressure the value of which varies with the speed of theengine fed with fuel from the injection pump. I

The object of my invention is to provide a device of this kind which isbetter adapted to meet the requirements of practice than those known upto this time.

According to theinvention, I make use, to produce the pressure variablewith the speed which is to act upon the piston of said hydraulic ram, ofa volumetric pump driven at a speed proportional to that of the internalcombustion engine and in the delivery circuit of which there is provideda leak through an outlet the area of which increases when the deliverypressure of said volumetric pump increases as a consequence of anincrease of the speed of the engine, and vice versa. The variation ofarea of this outlet as a function of the speed serves to moderate thevariation of pressure acting upon the piston of the hydraulic ram. It isthus possible to obtain a variation of the advance of fuel injectionover a very wide range of different speeds.

It should be well understood that the term volumetric pump designates apump such that the delivery flow rate thereof is proportional to thespeed at which it is driven.

Other features of my invention will become apparent in the course of thefollowing detailed description thereof.

Preferred embodiments of my invention will be hereinafter described withreference to the accompanying drawings, given merely by way of exampleand in which:

FIG. 1 diagrammatically shows, in axial section, a fuel injection pumpmade according to the invention and in which the variable pressureacting upon the hydraulic ram is proportional to the speed at which thepump is driven.

FIG. 2 is a partial view diagrammatically showing a modification of thepump of FIG. 1, where the hydraulic ram is operated in accordance withthe load of the engine fed with fuel by the injection pump.

FIGS. 3 to 5 inclusive show a detail of FIG. 1 according to threemodifications, respectively.

The pump illustrated by way of example in FIG. 1 is a pump the piston ofwhich acts as a distributing valve so as to produce successive fuelinjections into the respective cylinders of an internal combustionengine from a single pump working chamber. This is a possibleapplication of the invention but this disclosure has no limitativecharacter.

The reciprocating movement of pump piston 1, which is slidable incylinder 2, is obtained from a hollow shaft 3 carrying a cam 4 whichacts upon the lower end of against which the lower end of piston 1 isapplied by a spring 7. The upper end of said spring bears against afixed piece which will be hereinafter referred to, whereas the lower endof said spring acts upon a cup-shaped member 8 bearing against ashoulder 9 provided at the lower end of piston 1, a plate 10 beinginterposed between said shoulder 9 and push-piece 6 so as to reduce thefriction between the piston and the push-piece when the piston has, inaddition to its reciprocating movements, a movement of rotation aboutits axis, as hereinafter explained.

Fuel is fed to the working chamber of cylinder 2, that is to say theportion of said cylinder located above piston 1, through a feed conduit11 provided in the side wall of the cylinder and a conduit 12 providedin piston 1, fuel feed taking place when these two conduits 11 and 12register with each other, which is for instance the case when piston -1is in its lower dead center position, as illustrated by the drawing.Furthermore, the side wall of cylinder 2 is provided with a plurality ofdelivery conduits 13 (only one of which is shown by FIG. 1) eachprovided with a check-valve 14. Each of these delivery conduits is,during one delivery stroke, in communication with the working chamber ofcylinder 2 through a groove 15 provided in the side wall of piston 1.Said piston is rotated about its axis through means which will behereinafter described, so that it acts as a distributing valve. It willbe understood that the delivery of fuel through each of said conduits 13and the feed of fuel to an injector (not shown) to which said deliveryconduit leads begins as soon as piston 1, at the beginning of its upwardstroke (delivery stroke), has separated conduits 11 and 12 from eachother.

Camshaft 3 is rotated through a shaft 16 journalled, for instancethrough bearings 17 and 18, in the casing 19 of the pump. This shaft 16is driven in such manner by the shaft of the engine fed with fuel by theinjection pump that the instantaneous angular positions of shaft 16always correspond to the same instantaneous angular positions of theengine driving shaft. Hollow shaft 3 is mounted on an extension 16a ofshaft 16 so as to be able to rotate about said shaft without howeverbeing able to move axially with respect thereto. The coupling connectionbetween shaft 16 and shaft 3 is ensured by a threaded sleeve 20 providedwith helical teeth of small obliquity 21, 22, in mesh with correspondinghelical teeth carried, respectively, by shaft 16 and shaft 3. Teeth 21,22 are inclined in opposite directions. It will be understood that saidsleeve 21 serves to couple shafts 16 and 3 together, while producing avariation of the angular position of shaft 3 with respect to shaft 16when it is displaced in the axial direction. Such a variationcorresponds to a variation of the advance of fuel injection by the pump.

In order to produce this axial displacement of sleeve 20 in accordancewith variations of the speed or of the load of the engine supplied withfuel by the injection pump, I provide an annular hydraulic ram or jacksurrounding sleeve 20 and disposed in the casing 19 of the pump. I thusobtain a considerable reduction of the total volume of the pump and Imake use only of pieces of revolution which are easy to machine.

The tubular piston 23 of said ram is a stepped piston including twoportions which are slidably fitted in two respective bores 24, 25 ofdifierent respective diameters of the pump casing. Thus, a free space 26exists between the shoulder separating the outer surfaces of steppedpiston 23 and the shoulder separating the cylindrical walls of bores 24and 25. This free space 26 constitutes the variable volume workingchamber of the hydraulic ram,

to which is fed a fluid the pressure of which varies with the speed ofthe engineand which tends to move stepped piston 23 toward the left,against the action of a return spring 27.

- The annular shoulder of piston 23 preferably acts, as illustrated,through a coupling ring or annular plate 52 cooperating with a flange orcollar 51 of threaded sleeve 20. 'Ihus the cooperating surfaces ofannular plate 52 on the one hand and flange 51 and the annular shoulderof piston 23 on the other hand are in frictional contact with oneanother respectively over large areas, so that piston 23 is driven inrotation by sleeve 20 with some slipping with respect to ring 52, whichincreases the sensitivity of response of piston 23 to variations of theforces acting thereon to move it axially.

In order further to facilitate the rotation of piston 23,

spring 27 does not bear, at one of its ends, directly against piston 23but against a flange 51 of sleeve 20. The other end of spring 27 bearsagainst a shoulder 53 of an annular element 54 interposed between therotating ring 17a of bearing 17 and a shoulder of shaft 16. Therefore,both ends of spring 27 bear against rotating pieces in turn togetherwith them about the axis of shaft 16. This further has the advantage ofprotecting spring 27 against torsional stresses. Friction ring or plate52 is advantageously provided, on both of its faces, with radiallubricating grooves 55. When thepressure of the liquid in the workingchamber 26 of the hydraulic ram increases, piston 23 and thereforesleeve 20 are moved toward theleft, which produces a rotation of shaft 3with respect to shaft 16 in one direction, whereas the movement ofpiston 23, and therefore the rotation of shaft 3 with respect to shaft16, takes-place in the opposed direction when the pressure in theworking chamber 26 decreases.

Preferably, as shown, the portion of piston 23 which is slidable in bore25 is so dimensioned that the edge 23a .of said piston portion is alwayson the outside of said bore and never enters therein. This prevents anypossibility of jamming of the ram.

The pressure variations in the working chamber 26 of the ram areproduced by a volumetric pump, as above It should be noted that in ahydraulic ram such as above described, it is [impossible to avoid someleakage which reduces the pressure of the fuel supplied in workfed withfuel by the injection pump, for instance at idling,

speeds, say at speeds averaging 500 revolutions/minute, the deliverypressure of said auxiliary volumetric pump 31, 32 may becomeinsuffi'cient, due to the existence of such a leakage, to feed fuel tothe injection pump. This danger is particularly great when the engine isbeing started by cold weather. On the contrary, for higher speeds of theengine, the delivery pressure of the volumetric pump 31, 32 is quitesuflicient, despite the above mentioned leakage, and even requires theaction of the moderating valve 56. On the other hand, at low speeds ofthe engine, there is no utility in obtaining a correction of the advanceof fuel injection. This may remain con-' stant for speeds of the engineup to for instance 800 revolutions/minute.

In view of these facts, I provide a closing valve 59 in conduit 33 at apoint thereof downstream of that where feed conduit 58 branches off fromconduit 33 and also downstream of the leak producing means 34.Preferably. this closing valve is controlled in accordance with thedelivery pressure of volumetric pump 31, 32, that is to for instancebelow 800 revolutions/minute, valve 59 cuts f ofi the delivery of pump31, 32 from the working chamber 26 of the ram and any leakage as mayexist in this ram can have no effect on the delivery pressure of thepump, which is determined exclusively by the leak producing means 34controlled by moderator valve 56. It

defined, for instance a gear pump 31, 32 driven at a speed proportionalto that of the internal combustion engine and which delivers liquid intoa condui-t33 provided with a discharge outlet forming a leak 34, saidconduit 33 leading to the working chamber 26 of the ram. It is knownthat with such an arrangement the pressurerin chamber 26 increases whenthe speed of rotation of pump 31, 32 increases, and inversely. In orderto avoid too sudden variations ofpressure, the cross-section area of theoutlet forming the leak is controlled by a moderating valve. Such avalve is constituted, inthe embodiment illustrated, by. a piston. 56subjected in onejdirection to the pressure existing in conduit 33, and,in the other direction, to the action of an opposing spring 57. Thewhole is arranged in such manner that said moderating valve increasesthe area of the outlet forming the leak when the pressure in conduit 33increases and reduces said cross-section area when this pressure inconduit 33, decreases. In order to obtainthe best possible variation ofthe advance of fuel injection for every internal combustion engine, theshape of the outline of the outlet through which liquid can leak outisrsuitably chosen (circular, rectangular, triangular, or other shape)so that the variation of pressure in chamber 26 takes place according toa law corresponding to the desired variation of theadvance of fuelinjection. 7

Gear pump 31, 32 is driven by hollow shaft 3 which drives the gear 32 ofsaid pump through a toothed wheel 35. V 7

In the pump shown by FIG. 1, auxiliary pump 31, 32 serves both to supplythe control pressure for the hydraulic ram and to feed fuel to thecylinder of the injection pump through a conduit 58 which connects thefeed conduit 11 of the injection pump with the delivery conduit 33 ofpump 31, 32.

is only when the speed of the engine increases above 800revolutions/minute that the delivery pressure of pump 31, 32 movesclosing valve 59 sufdciently to open the communication between pump 31,32 and the ram.

The pump illustrated by the drawings comprises selfregulating means forcontrolling, in accordance With the speed, the flow rate of the pump percycle thereof. Said means operate on the basis of the so-called liquidabutment phenomenon. Such self-regulating means comprise a controlmember 36 called shuttle which, during the delivery stroke of the piston1 of the pump, moves upwardly under the effect of a liquid delivered byan auxiliary piston 37 which is integral with the main piston 1 andwhich cooperates with an auxiliary cylinder 38; At the end of its upwardstroke, which is determined by theopening of a discharge conduit 39, theshuttle opens another discharge conduit 40 in communication with theworking chamber of cylinder 2 so that the opening of said dischargeconduit 40 stops injection. During the downward stroke of pistons 1 and37, shuttle 36 also moves in the downward direction under the action ofa return spring 41, but this movement is slowed down due to the factthatthe shuttle must force the liquid located under it, through a throttledpassage 42, preferably adjustable by means of a screw 43. Consequently,when the speed of the pump exceeds a given value, shuttle 36 has not hadtime, during its downward strokes, to come back to its lowermostposition when a new stream of liquid is supplied into the space below itto produce the nextupward stroke thereof. The stroke is thereforeshortened, which advances the time when the shuttle opens shaped wheel45. In the hub 46 of said wheel 45 there is provided a longitudinalgroove 47 which cooperates with a radial projection 4 carried bypiston 1. The Whole is arranged in such manner that piston 1 can haveits reciprocating movements under the effect of cam 4, while being ableto rotate about its axis under the action of elements 3, 35 and 45.

It should also be noted that the bell-shaped Wheel 45 rotates in ahousing 49 of casing 19 which acts as a guide and bears against a needlebearing 51?.

In the pump shown by FIG. 1, the pressure produced in the workingchamber 26 of the ram and consequently the advance of fuel injectiondepend upon the speed of the engine which is fed with fuel from theinjection pump. When this speed does not vary or varies a little andwhen it is desired to vary this advance to fuel injection as a functionof the load of the engine, it is advantageous to have recourse toanother feature of the invention which is based upon the fact that theload depends upon the amount of fuel that is truly injected into theengine. As already stated, adjustment of this amount takes place in suchmanner that only a portion of the fuel displaced by the piston 1 of thepump during its delivery stroke is sent toward the injector, whereasanother portion is discharged to the outside. Of course, the amount offuel that is truly injected is the smaller as the discharged amount isgreater. Therefore I make use of the variation of the amount of fueldischarged to the outside to control the pressure in the working chamberof the hydraulic ram.

An embodiment of such a system is shown by FIG. 2. This figure shows amodification of the injection pump of FIG. 1, in which the variablepressure in working chamber 26 depends upon the load of the engine.

In this FIG. 2, the discharge conduit it} through which fuel deliveredby the piston l of the pump is evacuated after said discharge conduithas been cleared .by shuttle 36 is connected to a conduit 3.10 whichopens into the Working chamber 26 of the hydraulic ram. A discharge leakis provided at 34a in this conduit 49, 33a. Furthermore, a liquidpressure accumulator 44 is connected with conduit 33a. This accumulatorconstitutes a closed space partly filled with the fuel so that, betweenthe upper level of this fuel and the top .of this space, there isproduced an air cushion 44a the pressure of which depends upon the levelof the liquid. It will be readily understood that the pressure inconduits 43 and 33a, and consequently also in working chamberlfi, isthegreater as the amount of fuel evacuated from cylinder 2 throughdischarge conduit 40 is greater and therefore as the load of the engineis lower.

FIG. 2 diagrammatically shows, in the form of a screw 34a, means forvarying the section of passage for the leak, but of course said meansmight be automatically arranged as shown by FIG. 1.

Of course, my invention is not limited to the case where regulation ofthe fuel injection pump is obtained on the liquid abutment principle.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and efficient embodiments of my invention,it should be well understood that I do not wish to be limited thereto asthere might be changes made in the arrangement, disposition and form ofthe parts without departing from the principle of the present inventionas comprehended within the scope of the accompanying claims.

' What I claim is: V v

1. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for reciprocating movement in said cylinder, arotating member having its axis located in fixed position with respectto said cylinder, said rotating member being operatively connected withsaid piston for imparting thereto said reciprocating movement, a drivingshaft coupled with said engine and in line With said rotating member, athreaded sleeve in mesh both with said shaft and with said rotatingmember for coupling them in rotation, both said shaft and said memberbeing fixed in the direction of their common axis with respect to saidcylinder and said sleeve being movable axially with respect to saidshaft and said member so that axial displacement of said sleeve withrespect to said shaft and said member varies the angular setting of saidrotating member with respect to said shaft, a hydraulic ram comprisingon the one hand, a casing fixed with respect to said cylinder andprovided with a cylindrical recess coaxial with said shaft and saidmember and on the other hand a ram piston fitting slidably in saidrecess, said recess and said ram piston limiting between them a workingchamber for liquid under pressure, said ram piston being operativelyconnected with said sleeve for transmitting thereto the liquid pressurein said working chamber, resilient means operatively connected with saidram piston for yieldingly opposing the action of said liquid pressure onsaid ram piston, whereby variation of said liquid pressure causes achange in the phase relation between the cycle of operation of said fuelinjection pump and the cycle ofoperation of said internal combustionengine fed by said pump, a volumetric pump, means operatively connectedto said driving shaft and to said volumetric pump for driving the latterat the speed proportional to that of said engine, conduit means leadingfrom the output of said volumetric pump to said Working chamber of saidram, and means mounted in said conduit means to produce a leak of liquidtherefrom the greater as the liquid pressure in said conduit meansupstream of said leak producing means is higher, said leak producingmeans comprising a cylinder in communication at one end with saidconduit means, a piston slidable in said cylinder, one Wall of saidcylinder being provided with a longitudinal outlet slot of a widthvarying along its length, said slot being partly closed by said piston,and resilient means operatively connected with said last mentionedpiston to urge it in the direction tending to reduce the portion of saidslot uncovered by said last mentioned piston, the shape of said slotbeing adapted to produce a predetermined law of variation of theuncovered portion thereof as a function of the liquid pressure in saidconduit means.

2. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for reciprocating movement in said cylinder, arotating member having its axis located in fixed position with respectto said cylinder, said rotating member being operatively connected withsaid piston for imparting thereto said reciprocating movement, a drivingshaft coupled with said engine and in line with said rotating member, athreaded sleeve in mesh both with said shaft and with said rotatingmember for coupling them in rotation, both said shaft and said memberbeing fixed in the direction of their common axis with respect to saidcylinder and said sleeve being movable axially with respect to saidshaft and said member so that axial displacement of said sleeve withrespect to said shaft and said member varies the angular setting of saidrotating member with respect to saidshaft, a hydraulic ram comprising onthe one hand, a casing fixed with'respect to said cylinder and providedwith a cylindrical recess coaxial with said shaft and said member and onthe other hand a ram piston fitting slidably in said recess, said recessand said ram piston limiting between them a working chamber for liquidunder pressure, said ram piston being operatively connected with saidsleeve for transmitting thereto the liquid pressure in said workingchamber, resilient means operatively connected with said ram piston foryieldingly opposing the action of said liquid pressure on said rampiston, whereby variation of said liquid pressure causes a change in thephase relation between the cycle of operation of said fuel injectionpump and the cycle of operation of said internal combustion engine fedby said pump, a volumetric pump, a conduit for placing the output ofsaid volumetric pump in communication with said injection pump cylinderfor feeding fuel thereto, means operatively connected to said drivingshaft and to said volurnetric'pump for driving the latter at a speedproportional to that of said engine, conduit means leading from theoutput of said volumetric pump to said working chamber of said ram,means mounted in said conduit means to produce a leak of liquidtherefrom, said leak being the greater as the liquid pressure in saidconduit means upstream of said leak producing means is higher, valvemeans for opening or closing said conduit means, said valve means beinglocated in said conduit means downstream of'said leak producing meansand downstream of the. place where said conduit leads from saidvolumetric pump output to said fuel injection pump, said valve meansbeing responsive to the pressure in said conduit means for closing saidconduit means when said pressure is below a given value and opening saidconduit means when said pressure exceeds said given value.

3. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for reciprocating movement in said cylinder, arotating member having its axis located in fixed position with respectto said cylinder, said rotating member being operatively connected withsaid piston for imparting thereto said reciprocating movement, a drivingshaft coupled with said engine and in line with said rotating member, athreaded sleeve surrounding adjoining portions of said shaft and saidrotating member and in mesh with said portions for coupling them inrotation, both said shaft and said member being fixed in the directionof their common axis with respect to said cylinder and said sleeve beingmovable axially with respect to said shaft and said member so that axialdisplacement of said sleeve with respect to said shaft and said membervaries the angular setting of said rotating member with respect to saidshaft, a hydraulic ram comprising on the one hand, a casing fixed withrespect to said cylinder and provided with a cylindrical recess coaxialwith said shaft and said member and on the other hand a ram pistonfitting slidably in said recess, said recess and said ram pistonlimiting between them a working chamber for liquid under pressure, saidram piston being operatively connected with said sleeve for transmittingthereto the liquid pressure in said working chamber, resilient meansoperatively connected with said ram piston for yieldingly opposing theaction of said liquid pressure on said ram piston, whereby variation ofsaid liquid pressure causes a change in the phase relation between thecycle of operation of said fuel injection pump and the cycle ofoperation of said internal combustion engine fed by said pump, means forfeeding said working chamber of said ram with liquid at a pressurevariable in response to variations of a factor ofoperation of said pump,and coupling means between said ram piston and said shaft fortransmitting by friction a rotary movement about said shaft axis to saidram piston. V

4. A system acording to claim 3 in whichsaid last mentioned means haveannular friction surfaces of a mean diameter approximately equal to thediameter of said piston and said sleeve.

5. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for reciprocating movement in said cylinder, arotating mem her having its axis located in fixed position with respectto said cylinder, said rotating member being operatively connected withsaid piston for imparting thereto said reciprocating movement, a drivingshaft coupled with said engine and in line with said rotating member, athreaded sleeve surrounding adjoining portions of said shaft and saidrotating member and in mesh with said portions for coupling them inrotation, both said shaft and said mem ber being fixed in the directionof their common axis with respect to said cylinder and said sleeve beingmovable axially with respect to said shaft and said member'so that axialdisplacement of said sleeve with respect to said shaft and said membervaries the angular setting of said rotating member with respect to saidshaft, 21 hydraulic ram comprising on the one hand, a casing fixedwithrespect to said'cylinder and provided with a cylindrical re cesscoaxial with said shaft and said member and on the other hand a rampiston fitting slidably in said recess; said recess and said ram pistonlimiting between them a working chamber for liquid under pressure, saidram piston being operatively connected with said sleeve for transmittingthereto the liquid pressure in said working chamber, resilient meansoperatively connected with said, ram piston for yieldingly opposing theaction of said liquid pressure on said ram piston, whereby variation ofsaid liquid pressure causes a change in the phase relation between thecycle of operation of said fuel injection pump and the cycle ofoperation of said internal combustion engine fed by said pump, means forfeeding said Working chamber of said ram with liquid at a pressurevariable in response to variations of a factor of operation of saidpump, and coupling means between said ram piston and said sleeve fortransmitting by friction a rotary movement about said shaft axis fromsaidsleeve to said ram piston, said casing recess comprising twocylindrical por-' tions of different respective diameters in line witheach other and connected together by an annular wall portion transverseto said axis, said ram piston being a tubular stepped piston coaxiallysurrounding said sleeve and comprising two portions of differentdiameters adapted to fit slidably in said recess portions respectivelyand connected together by an annular wall portion transverse to saidaxis, said working chamber being located between said recess annularwall portion and the face of said ram piston annular wall portion turnedtoward it, said sleeve carrying a flange on the other side of said ram'piston annular wall portion from said working chamber and said couplingmeans being between said sleeve flange and the face of said ram pistonannular wall portion turned toward it.

8. A system according to claim 5 further including an annular part fixedto said driving shaft to form an outward projection around it, said partbeing located at'a distance from saidsleeve flange and on the other sidethereof from said working chamber, said resilient means operativelyconnected with said ram piston consisting of a spring interposed betweensaid annular part and said sleeve flange.

9. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for 're-.

ciprocating movement in said cylinder, a rotating member having its axislocated in fixed position with respect 7 to said cylinder, said rotatingmember being operatively connected with said piston for impartingthereto said reciprocating movement, a driving shaft coupled with saidengine and in line with said rotating member, a threaded sleevesurrounding adjoining portions of said shaft and said rotating memberand in mesh with said portions for 7 coupling them in rotation, bothsaid shaft and said member being fixed inthe direction of their commonaxis with respect to said cylinderand said sleeve being movable axiallywith respect to said shaft and said member so that axial displacement ofsaid sleeve with respect to said shaft and said member varies theangular-setting of said rotating member with respect to said shaft, ahydraulic ram comprising on the one hand, a casing fixed with respect tosaid cylinder and provided with a cylindrical recess coaxial with saidshaft and said member and on the other hand a ram piston fittingslidably in said recess, said recess and said ram piston limitingbetween them a working chamber for liquid under pressure, said rampiston being operatively connected with said sleeve for transmittingthereto the liquid pressure in said working chamber, resilient meansoperatively connected with said ram piston for yieldingly opposing theaction of said liquid pressure on said ram piston, whereby variation ofsaid liquid pressure causes a change in the phase relation between thecycle of operation of said fuel injection pump and the cycle ofoperation of said internal combustion engine fed by said pump, means forfeeding said working chamber of said ram with liquid at a pressurevariable in response to variations of a factor of operation of saidpump, and coupling means between said ram piston and said shaft fortransmitting by friction a rotary movement about said shaft axis fromsaid shaft to said ram piston, said casing recess comprising twocylindrical portions of different respective diameters in line with eachother and connected together by an annular wall portion transverse tosaid axis, said ram piston being a tubular stepped piston coaxiallysurrounding said sleeve and comprising two portions of differentdiameters adapted to fit slidably in said recess portions respectivelyand connected together by an annular wall portion transverse to saidaxis, said working chamber being located between said recess annularwall portion and the face of said ram piston annular wall portion turnedtoward it.

10. A system according to claim 9 in which the greatest part of saidsleeve is located inside the portion of smaller diameter of said tubularstepped piston.

11. A system according to claim 9 in which the cylindrical portion ofsaid casing recess that is closer to said rotating member is shorter, inthe axial direction, than the portion of said stepped piston that ishoused therein.

12. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for reciprocating movement in said cylinder, arotating memher having its axis located in fixed position with respectto said cylinder, said rotating member being operatively connected withsaid piston for imparting thereto said reciprocating movement, a drivingshaft coupled with said engine and in line with said rotating member, athreaded sleeve in mesh both with said shaft and with said rotatingmember for coupling them in rotation, both said shaft and said memberbeing fixed in the direction of their common axis with respect to saidcylinder and said sleeve being movable axially with respect to saidshaft and said member so that axial displacement of said sleeve withrespect to said shaft and said member varies the angular setting of saidrotating member with respect to said shaft, a hydraulic ram comprisingon the one hand, a casing fixed with respect to said cylinder andprovided with a cylindrical recess coaxial with said shaft and saidmember and on the other hand a ram piston fitting slidably in saidrecess, said recess and said ram piston limiting between them a workingchamber for liquid under pressure, said ram piston being operativelyconnected with said sleeve for transmitting thereto the liquid pressurein said working chamber, resilient means operatively connected with saidram piston for yieldingly opposing the action of said liquid pressure onsaid ram piston, whereby variation of said liquid pressure causes achange in the phase relation between the cycle of operation of said fuelinjection pump and the cycle of operation of said internal combustionengine fed by said pump, an auxiliary liquid pump, means operativelyconnected to said driving shaft and to said volumetric pump for drivingthe latter at a speed proportional to that of said engine, conduit meansleading from the output of said auxiliary pump to said working chamberof said ram, and means in communication with said conduit means forcontrolling the pressure of the liquid fed to said ram working chamberto give said pressure a value variable in response to variations of afactor of operation of said pump, said pressure controlling meanscomprising means mounted in said conduit means to produce a leak ofliquid therefrom the greater as the liquid pressure in said conduitmeans upstream of said leak producing means is higher, said leakproducing means comprising a cylinder in communication at one end withsaid conduit means, a piston slidable in said cylinder, one wall of saidcylinder being provided with a longitudinal outlet slot of a widthvarying along its length, said slot being partly closed by said pistonand resilient means operatively connected with said last mentionedpiston to urge it in the direction tending to reduce the portion of saidslot uncovered by said last mentioned piston, the shape of saidslot-being adapted to produce a predetermined law of variation of theuncovered portion thereof as a function of the liquid pressure in saidconduit means.

'13. A fuel injection system for an internal combustion engine whichcomprises, in combination, a fuel injection pump including a cylinderand a piston mounted for reciprocating movement in said cylinder, arotating member having its axis located in fixed position with respectto said cylinder, said rotating member being operatively connected withsaid piston for imparting thereto said reciprocating movement, a drivingshaft coupled with said engine and in line with said rotating member, athreaded sleeve in mesh both with said shaft and with said rotatingmember for coupling them in rotation, both said shaft and said memberbeing fixed in the direction of their common axis with respect to saidcylinder and said sleeve being movable axially with respect to saidshaft and said member so that axial displacement of said sleeve withrespect to said shaft and said member varies the angular setting of saidrotating member with respect to said shaft, a hydraulic ram comprisingon the one hand, a casing fixed with respect to said cylinder andprovided with a cylindrical recess coaxial with said shaft and saidmember and on the other hand a ram piston fitting slidably in saidrecess, said recess and said ram piston limiting between them a workingchamber for liquid under pressure, said ram piston being operativelyconnected with said sleeve for transmitting thereto the liquid pressurein said working chamber, resilient means operatively connected with saidram piston for yieldingly opposing the action of said liquid pressure onsaid ram piston, whereby variation of said liquid pressure causes achange in the phase relation between the cycle of operation of said fuelinjection pump and the cycle of operation of said internal combustionengine fed by said pump, a volumetric pump, a conduit for placing theoutput of said volumetric pump in communication with said injection pumpcylinder for feeding fuel thereto, means operatively connected to saiddriving shaft and to said volumetric pump for driving the latter at aspeed proportional to that of said engine, conduit means leading fromthe output of said volumetric pump to said working chamber of said ram,means mounted in said conduit means to produce a leak of liquidtherefrom, valve means for opening or closing said conduit means, saidvalve means being located in said conduit means downstream of said leakproducing means and downstream of the place where said conduit leadsfrom said volumetric pump output to said fuel injection pump, said valvemeans being responsive to the pressure in said conduit means for closingsaid conduit means when said pressure is below a given 11" value andopening said conduit means when said pressure exceeds said givenvalue.

'References Cited in the file of this patent v UNITED STATES PATENTS 51,736,242 Attendu Nov'; 19, 1929 12 V Schaeren -2 Oct. 24, 1939Fischlmayr Dec. 15, 1942 Hogeman Jan. 6, 1953" Aldinger et a1. Sept. 1,1959 Evans Nov. 3, 19 5 9

